Mattress



FIG. 1 is a perspective view of a mattress.

FIG. 2 is a top view and a bottom view of the mattress of FIG. 1.

FIG. 3 is a back end view of the mattress of FIG. 1.

FIG. 4 is a right side view of the mattress of FIG. 1.

FIG. 5 is a front end view of the mattress of FIG. 1; and,

FIG. 6 is a left side view of the mattress of FIG. 1. 

CLAIM The ornamental design for mattress, as shown and described. 